Crepe thread and fabric



Patented Jan. 3, 1939 e 2 UNITED STATES W H V 2,142,118

2,142,118 CREPE THREAD AND FABRIC Henry Dreyfus, London, England No Drawing. Application January 30, 1935, Serial No. 4,082. In Great Britain February 8, 1934 4 Claims.

This invention relates to the manufacture of crepe threads and fabrics, and has for its particular object the production of crepe fabrics of an improved character from threads containing artificial filaments.

Fabrics exhibiting crepe effects have long been obtained by employing in their construction highly twisted threads of natural silk in the gummed state, the crepe effects appearing more particularly when the fabric so formed is subjected to an aqueous scouring treatment. The fabrics ob tained by this process are highly valued on account of their pleasing appearance and handle. The production of crepe fabrics in an analogous manner by the use of threads containing artificial filaments has, however, been accompanied by difficulties in various directions, particularly as regards the strength and appearance of the fabrics.

I have new found that considerable improvement can be effected by employing crepe threads containing artificial filaments of cellulose derivatives of high viscosity characteristic, for example cellulose acetate or other cellulose esters as described in U. S. Patent No. 1,708,787. Thus cellulose acetate shouldhave a viscosity of at least 30 and preferably exceeding 50, for example, of the order of 75, 100, 150, or even 200 or more as measured by comparing the viscosity of a 6% solution of the cellulose acetate in acetone with that of glycerine taken as a standard of 100.

In addition to the cellulose derivatives above mentioned, there may be employed organic cellulose esters such as cellulose formate, propionate, butyrate, and oxyethyl cellulose acetate, and cellulose ethers such as ethyl and benzyl cellulose.

The threads of high viscosity cellulose derivatives have a strength as compared with those of normal viscosity which is of advantage when the threads are subjected to the high degree of twist necessary for the production of crepe effects, the threads having a higher strength when twisted.

Threads of high viscosity cellulose acetate or other cellulose esters may, however, be saponified to give the additional advantage of better figure in the crepe fabrics in which they are employed. Such saponification may be complete or only partial. In partially saponified materials the saponification may be superficial, i. e. the materials may comprise a superficial layer consisting substantially of cellulose or of esters of cellulose of low acyl content, and a core of substantially unchanged cellulose ester. Such materials are readily obtainable by processes in which cellulose ester materials are impregnated with a saponifying agent, for example aqueous, aqueous-alcoholic, or alcoholic caustic soda during their continuous passage between two points, and are immediately thereafter subjected to elevated temperatures, for instance by passing them over heated drums or the like, so as to effect rapid drying and saponification as described, for example, in U. S. Patents Nos. 1,884,622 and 1,884,623.

t is in general preferable, however, to employ materials in which saponification has extended considerably below the surface or even throughout the whole section of the material. The saponification may be of a very low order, for example sufiicient to produce a loss in weight of 5% or even less. Specially valuable results are obtainable by employing materials which have been saponified so as to effect a loss of weight of between 5 and 20%, and particularly between 8 and 12%. Products of this type in which the saponification extends considerably below the surface or throughout the whole of the material are specially recommended. On the other hand, saponification may be of a much higher order, involving a loss of weight of 30, 40 or even 50% or more, according to the ester content of the initial material, up to complete saponification.

The saponified materials may acquire an affinity for cotton dyestuffs by the saponification treatment which may, or may not, involve loss of affinity for cellulose ester dyes, for example dyes of the dispersed insoluble type. It has been found of particular advantage in connection with cellulose acetate to carry the saponification to such an extent that the material is insoluble in acetone but yet retains a relatively high acetyl content.

The degree of twist applied to the threads according to the invention may vary within wide limits; for example twist from 45 to 75 or more turns per inch may be applied, it being understood that in general the finer the thread the higher the degree of twist required. Apart from this the degree of twist desirable in any particular case depends upon a number of other factors, including the precise effects required, the material of the filaments, and the fineness of the filaments in the threads. It is to be pointed out in this connection that fineness of the individual filaments in the threads is of considerable advantage in bringing out a good crepe effect on the final fabric, as well as lending itself to the production of fabric having a soft handle.

The twist is conveniently applied by means of an apparatus in which the thread is drawn off over the end of a rotating package to a guide substantially in line with the axis of the package, and thereupon led to a take-up device collecting the yarn at a predetermined speed which determines in accordance with the rate of rotation of the package the degree of twist applied. The rotating bobbin may be provided with a fiyer to guide the thread from the package, or with advantage the twisting device may be provided with means on an extension of the spindle projecting beyond the package to prevent twist which has been inserted running back to the yarn on the package.

During twisting the thread may be subjected to the action of wet steam, as by passing it through a steam box disposed between the guide above the spindle and the take-up package. Thread twisted in this way has a final strength considerably higher than that obtained by twisting untreated thread.

The tension maintained during twisting may be such as under the action of the applied steam to stretch the thread and overcome in part at least the tendency of the thread to increase in denier during twisting. However, even if the twist is allowed to give a denier increase, higher final tenacities are obtained. 7

The improved crepe threads according to the invention may be applied in any desired manner in the weaving of crepe fabrics either in the weft or warp or both and with any suitable disposition as regards threads having leftand righthand twists, as for example leftand right-hand twists alternating singly or in pairs in the weft. The threads may also be used otherwise than in woven fabrics; for example, they may be knitted.

What I claim and desire to secure by Letters Patent is:- I

1. Process for the production of crepe threads which comprises saponifying, substantially uniformly along their length and to a depth at least considerably below their surface, threads of cellulose acetate having a viscosity of at least 30, measured as hereinbefore defined, to a degree such that 5-20% of the weight of the cellulose acetate is lost, and twisting the threads to a high degree while simultaneously applying steam to.

the part of the threads where the twisting is being inserted.

2. Process for the production of crepe threads which comprises .saponifying, substantially uniformly along their length and to a depth at least considerably below their surface, threads of cellulose acetate having a viscosity of at least 50, measured as hereinbefore defined, to a degree such that 8-12% of the weight of the cellulose acetate is lost, and twisting the threads to a high degree while simultaneously applying wet steam to thepart of the threads where the twist is being inserted.

3. Process for the production of crepe threads which comprises saponifying, substantially uniformly along their length and to a depth at least considerably below their surface, threads containing a cellulose ester having a viscosity of at least 30, measured as hereinbefore defined, to a degree such that 520% of the weight of the cellulose ester is lost, and twisting the threads to a high degree while simultaneously applying steam to the part of the threads where the twist is being .inserted.

4. Process for the production of crepe threads which comprises saponifying, substantially uniformly along their length and to a depth at least considerably below their surface, threads containing a cellulose ester having a viscosity of at least 50, measured as hereinbefore defined, to a degree such that 842% of the weight of the cellulose ester is lost, and twisting the threads to a high degree while simultaneously applying Wet steam to the part of the threads where the twist is being inserted.

HENRY DREYFUS. 

